1. Field of the Invention
The invention relates to a one-piece plastic element as defined by claim 1, to a piston pump for a hydraulic brake system, and to an assembly method.
2. Description of the Prior Art
Piston pumps are used in hydraulic brake systems of motor vehicles and are often called return feed pumps. In a traction control mode, they serve to lower or raise the brake pressure in the wheel brake cylinders selectively so as to be able to regulate the brake pressure in the wheel brake cylinders.
German Patent Disclosure DE 197 327 70 A1 shows a piston pump with an inlet valve embodied as a check valve; the inlet valve has a cup-shaped inlet valve cap embodied as a deep-drawn sheet-metal part. The inlet valve cap is urged by spring pressure in the axial direction by means of a restoring spring for a pump piston. A closing spring element and a closing body are disposed inside the inlet valve cap. The closing body is urged by spring pressure by the closing spring element onto a valve seat, which is disposed on the face end of the pump piston.
Piston pumps have also become known in which the cup-shaped inlet valve cap is embodied as a plastic element, and in which the valve seat of the inlet valve is not disposed directly on the pump piston but rather on a separate inlet valve element from the inlet valve cap that is affixed to the pump piston. The assembly of the known piston pumps is complicated, since the inlet valve cap and the inlet valve element have to be installed separately from one another. Moreover, the production of the individual components (the inlet valve cap and the inlet valve element) is cost-intensive.